Preheater for type and lead casting machines



Sept. 11, 1928.

R. J. ROBERTS PREHEATER FOR TYPE momma CASTING mcamns Filled Sept. 24, 1927 w mi w ww wv 1 L 3 m t 5.

Patented Sept. 11, 1928.

RICHARD J. ROBERTS, 01 SAN FRANCISCO, CALIFORNIA.

PREHEATER; 1303- TYPE AND LEAD C'KSTING MACHINES;

Application fi'lcd'- Septenfber 24, 192. Serial No. 221,745.

My invention relates to preheaters for melting metal preparatory for introduction into lead and slug casti-Irg machines and the like.

In the operation of lead and slug casting machines, and the like, pigs of casting metal are inserted in a melting pot forming a part of the casting machine. Said melting pots are heated 1nvarious ways, but as the consumption of melted metal is very rapid; when the machine is in operation, the very frequent introduction of cold pigs of metal into the pot cools the metal and retards the ellicient operation at the machine, it being frequently necessary to slow down the machine or stop operation entirely until the supply of melted metal can. be built up to meet normal requirements. The primary object of my present invention is therefore to provide an improved device for preheating thecasting. metal. whereby the metal may be. delivered tothe melting pot of the machine preheated to a molten condition. whereby the requisite supply of metal for eilicicnt-operation of'the machine may be maintained atall times.

A further object isto provide an im proved device of the chaxacter described whereby metal to be supplied to at casting machine is melted by electrical means before being introduced into the machine;-

Another object is to provide arr improved electrically heated device wherein the electrical heating units are automatically cut out of the energizing circuit when the supply of metal; is cut off.-

A further object is to provide an improved device relatively light and. compact and. which ma be easily placed: inservice without altering. the machines and equipment to which it is applied.

A. still further object is to provide an improved device of the character described which is simple in construction and highly ellicient in operation.

I accomplish these and other objects by means of the improved device disclosed in the drawings forming a part of the present application wherein like characters of reference are used to designate similar parts throughout the specification and drawings, and in which,

Fig. 1 isa broken front elevation of: my improved. prcheater, the casing being shown in section, and parts beingbroken away;-

Fig. 2 is a vertical mid-section of the pro-- heater;

Fig. 3 is a plan: view 01 the prehcater; and

F ig. 4: is a broken side elevation including at) a, \viring diagram illustrating the automatic circuit breaking means;

Referring tothe drawings,- my improved preheater consists of a; pair of chamber blocks 1; bolted or otherwise secured to gether, said blocks having matching recemes' forming. a: chamber 2 arranged toreceivepigs of casting metal to be supplied t1;- a; lead.- and slug casting machine, or the like, not shown. An outlet 3, preferably at tubular metal of high heatingconductivity, is connected into the bottom oi the chamher 2.-

Electrical resistance heating units 4% are n'iounted' in proximate relation to the outer faces of the blocks 1,- said units being secured and: held in place by plate 6 seeured by screws or other suitable securing ele ments'l to hold the heating elements closely against the outer sides of the chamber blocks 1 Thin sheets 8 of mica or' other suitable electrical insulating matewial are inserted between the heating unit and the blocks 1 and plates 6.

The heating units are connected, in any suitable manner,- preferably in series, by suitable electrical connections 9 and secured by binding. posts 12 secured upon the base ofthe blocks 1-, said binding posts being connected to the units through conductors 13 preferably connected onto the ends of the posts 12 to permit the replacement of heating elementswithout disturbing the wiring connections. The unit 4 are connected toa suitable source ofelectrical energy, not shown, inany convenientman'- ner.

An automatic cut out switch designated in geueizil' by the numeral 16 is connected into the circuit to the heating units 4. outswitch may be of any arailableconstruct'on', a form beingconventionally illhstratcd wherein a movable contact; arm 17' is ar range-d txi be actuated'by a-r'elay 18 energized from. the feed connections 19 to break conm5 upon an arm 26-secured upon the outerend The cut [00 secured upon the outer endof the shaft-27 to normally move the lever 28 outwardly from the recess 29. and across the-chamber:- 2 as indicated in dotted lines in Fig. 2 of the drawings, and .at the same time to movethe arm 26 to carry the contact 23 into brid ing relation $043116 contacts 24 as indicate in dotted lines-.in 4.. I A control switch 25 is mounted at any convenient place to break theifeedconnections when desired.

r A casing .32 formed ofasbestos or other suitable heat insulating material is mounted to substantially.enclosethe'sides and bottom of the ipreheater and thereby reduce loss in heating-,efiiciency. A suitable bail" 33 is secured upon the top of the preheater-whereby the same may'be suspended in any convenient .manner over the. melting pot of a lead and slug casting machine.

In operation, my preheater is mounted or suspended by the bail 33 over the meltingpot ofthe casting machine, and connected to a source of electrical energy. When the castingmachine is .tobe laced in operation, the control switch 25 is. osed and a pig of metal to be melted and delivered to .the machine is inserted in the chamber 2,.said metal serving to .force the lever 28 into the recess 29 and thereby move the shaft to raise the counterweight 31 and at the same time move the arm 26 and contact 23 out of engagement with the ;contacts 24. The heating units are thus energized and operate to, rapidly heat the chamber. and melt the metal therein, said metal draining oil through the outlet 3 into the melting pot of the machine. After the initial heating of the chamber and when the first metal pig has been melted fresh pigs of the casting metal are inserted into the chamber at frequent intervals whereby a constant supply of melted metal may be delivered into the melting pot of the casting machine whereby said machine may be operated at full ciiiciency without cooling the metal in the melting pot by the introduction of metal pigs therein. So long as a supply of metal is maintained in the chamber 2, the lever 28 will remain in circuit closing position, and the-heating elements will remain operative to maintain the temperature of the preheater. Should the metal become exhausted, or should the main control switch be inadvertently left closed when the machine is not in operation, the counterweight, 29 operates by gravity to swing the arm 26 and contact 23 into engagement with the contacts 24, thereby closing a circuit through the relay 18 whereby the circuit is broken between the contacts 21 and 22, thereby cutting the heatingunits out of the circuit and thus preventing overheating of the units and the chamber, and preventing-the waste of electrical energy. The outlet 3 is of greater heat -conductivity than the chamber block 1 to insure that said outlet will prevent the freezing ofimetal within-the outlet.

It will be noted that the electrical heating elements are arranged entirely outside of the chamber so that there can be no danger of injury to the-elements should metal be permitted to harden within the chamber. At the sametime. the elements are rendered readily removable so that new elements can be quickly .installed when necessary.

While I have illustrated and described only the-.preferred embodiment of my invention, the device is of course subject to modificationin numerous ways without departing from thespirit of my invention. I therefore donot wish to restrict myself to the specific form and construction illustrated, and described, but desire to avail myself of all modifications which may fall within the scope of the appended claims.

Having thus described my invention what I claim as new and desire to secure by Letters Patent-is .1. -A preheat-er for leadand slug casting machines comprising a melting chamber ar ranged to receive pigs of casting metal; and electrical beatings units arranged outside of the chamber and connected to a source of electrical energy ,to heat said chamber whereby the metal may be melted for deliveryto the casting machine; and means forautomatically disconnecting the heating units from the source of energy when a supply of metal is not maintained within the chamber.

2. A preheater for lead and slug casting machines comprising a melting chamber arranged to receive pigs of casting metal; plutcs secured upon the outer surfaces of the chamber; and electrical heating units secured between the plates and the outer surfaces of the chamber, said units being connected to a. source of electrical energy for heating the chamber; current breaking means connected between the heating units and the source of electrical energy; and means controlled by the supply of metal within the chamber for actuating the circuit breaking means to break the circuit through the heating units when the supply of metal in the chamber is not maintained.

3. A prcheater for lead and slug casting machines con'iprising a melting chamber formed from a pair of blocks having matching recesses forming a chamber to receive pigs of casting metal; a pair of electrical heating units arranged to be connected ,to a source of electrical energy; and plates secured upon the outer surfaces of the blocks and arranged to hold the units in proximate relation to said outer surfaces for heating the chamber.

4. A preheater for lead and slug casting machine comprising a melting chamber formed from a pair of blocks having matching recesses forming a chamber to receive pigs of casting metal; a pair of electrical heating units arranged to be connectedto a source of electrical energy; and plates secured upon the outer surfaces of the blocks and arranged to hold the units in proximate relation ,to said outer surfaces for heating the chamber; and an outlet connected into the bottom of the chamber, said outlet being formed of metal having higher heat conductivity than the blocks to insure the draining of melted metal from the chamber.

5. A preheater for lead and slug casting machines comprisin a pair of cast iron blocks secured toget erand having matching recesses formed in their adjacent faces to form a chamber arranged to receive pigs of casting metal; a pair of metal plates secured upon opposite outer faces of the blocks; electrical heating units mounted between the plates and the blocks, said units being arranged to be connected to a source of electrical energy for heating the chamber; a cut out switch connected between the units and the source of energy; an automatic control lever mounted within the chamber and arranged to be held in cut out circuit breaking posit-ion by metal within the chamber; and means actuated by the lever and the cut out switch for automatically breaking the circuit when the supply of metal to the chamber is not maintained.

6. A preheater for lead and slug casting machines comprisin a pair of cast iron blocks secured toget er and having matching recesses formed in their adjacent faces to form a chamber arranged to receive pigs of casting metal; a pair of metal plates secured upon opposite outer faces of the blocks; electrical heating units mounted bet-ween the plates and the blocks, said units being arranged to be connected to a source of electrical energy for heating the chamber; a cut out switch connected between the units and the source of energy; an automatic control lever mounted within the chamber and arranged to be held in cut out circuit breaking position by metal within the chamber; and means actuated by the lever and the cut out switch for automatically breaking the circuit when the supply of metal to the chamber is not maintained; and a heat insulating casing substantially enclosing the chamber and heating elements.

In witness whereof, I hereunto set my signature.

RICHARD J. ROBERTS. 

